This invention relates generally to centrufigal pumps. More particularly, this invention relates to wear plate assemblies associated with such pumps. Still more particularly, this invention relates to apparatus for adjusting the position of such plate assemblies.
A typical centrufigal pump has an inlet chamber separated from an outlet chamber with an impeller chamber disposed therebetween. The impeller chamber houses an impeller having a series of vanes radially disposed about an impeller axis co-incidental with an impeller shaft. The impeller shaft is generally driven by a motor which causes it to spin. The impeller has a front face fluidly communicating with the inlet chamber through an aperture generally axially aligned with the impeller. The outlet chamber is disposed about the impeller chamber and fluidly communicates with the impeller chamber through fluid passages generally radially disposed about the impeller.
As fluid passes from the inlet chamber into the impeller housing, the spinning impeller displaces the fluid radially through centrufigal force imparted by the impeller causing the fluid to flow into the outlet chamber. An inlet port is provided into the inlet chamber for admitting fluid into the pump. An outlet or discharge opening is provided from the outlet chamber to discharge fluid from the pump. The inlet chamber, impeller chamber and outlet chamber are contained within a pump casing.
Maximum pumping efficiency requires relatively precise tolerances to be maintained between the impeller and the impeller chamber. With use, wear will incur which causes clearance to increase between the impeller and the impeller housing reducing the efficiency of the pump. In order to accommodate wear without having to replace the pump casing, a replaceable wear plate is provided between the impeller chamber and the impeller. Although the wear plate could be replaced once the pump wears, some designs provide for relative movement between the wear plate and the pump impeller to take up clearance without replacing any of the components.
One manner for taking up clearance is to provide shims between the wear plate and the pump casing which correspond in thickness to the amount of wear. Although this eliminates the need for replacing the casing or the wear plate, it nevertheless requires disassembly of the pump to insert the shims which is both time consuming and costly in down time period.
Various mechanism have been proposed for movably mounting the wear plate to enable adjustment without shimming. Some of these nevertheless require at least partial disassembly of the pump in order to make the adjustment. Others are rather complicated and costly, often being unserviceable through corrosion related seizure by the time adjustment is required.
It is an object of the present invention to provide an adjustable wear plate assembly for a pump which is accessible externally of the pump without pump disassembly. A further object of the present invention is to provide such a positioning assembly which is simple, relatively inexpensive and not prone to corrosion related seizures.
An adjustable wear plate positioning assembly is provided for a pump having a casing housing and an impeller and defining a circumferential and rear face of an impeller chamber disposed about the impeller. The pump further has a discharge chamber fluidly communicating with the impeller chamber and a discharge outlet for discharging fluid from the casing. An inlet chamber fluidly communicates with the impeller chamber, has an inlet port through the casing and provides a fluid passage to an inlet face of the impeller. The impeller chamber is further defined by a wear plate adjacent an inlet face of the impeller and has a fluid passage therethrough for admitting fluid axially into the fluid chamber. The casing has a front wall opposite the inlet face of the impeller and a partition wall dividing an inlet chamber from the outlet chamber. The adjustable wear plate positioning assembly has a wear plate carrier extending between the front wall and the partition wall. The wear plate carrier has an outer end slidingly received in a first aperture through the front wall remote from the inlet port and opposite the inlet face of the impeller. The wear plate carrier further has an inner end opposite the outer end slidably engaging a second aperture through the partition wall adjacent the inlet face of the impeller. The wear plate is rigidly securable to the inner end of the wear plate carrier and the inner end has a passage therethrough registering with the fluid passage through the wear plate. A mounting plate is disposed externally of the casing adjacent the front wall of the casing and secured to the outer end of the wear plate carrier. Adjustable limit means extend between the mounting plate and the front wall to limit movement of the flange and in turn the wear plate toward the impeller. Releasable locking means act between the front wall and the flange for securing the mounting plate in position relative to the front wall.
The adjustable limit means may include a plurality of set screws extending through the mounting plate and abutting against the front wall.
The releasable locking means may include a plurality of threaded fasteners extending between the front wall and the mounting plate.
The wear plate carrier may have a plurality of spaced apart struts extending between the inner and outer ends. The inner and outer ends may be generally annular and respective fluid sealing members may extend between the inner and outer ends and the first and second apertures.
The outer end of the wear plate may have a passage extending axially therethrough and a removable cover over the aperture to provide access to the impeller. The flange may be removably securable to the outer end and act as the cover.